Cross country pipelines for conveying fluids over great distances are usually wrapped with a special protective material and placed in the bottom of a ditch. As the temperature of the pipe changes, contraction and expansion of the metal pipe causes lateral movement of the buried pipeline. It is, therefore, necessary to pad the pipeline with small aggregate material, such as sand or crushed caliche, to assure that the pipe does not rub against sharp objects, such as large rocks, for example, and become damaged.
Machines for uniformly spreading material from some sort of hopper are known to those skilled in the art, as evidenced by the following patents:
U.S. Pat. No. 2,584,322--Baldwin et al PA1 U.S. Pat. No. 2,879,910--Johnson PA1 U.S. Pat. No. 3,065,556--Kampert PA1 U.S. Pat. No. 3,273,730--Moore PA1 U.S. Pat. No. 3,804,278--James, III PA1 U.S. Pat. No. 3,907,451--Fisher et al PA1 U.S. Pat. No. 3,981,089--Burrows PA1 U.S. Pat. No. 4,055,255--Vasquez
Very few of the above cited prior art devices are suitable for padding long cross country pipelines in the manner contemplated by the present disclosure. In the Burrows patent, for example, it is necessary to include a massive hopper for holding padding material therewithin, and it is doubtful that the hopper could be recharged while the machine is concurrently transporting the padding material into the pipeline ditch.
The present invention makes available a padding machine which continuously transports padding material into a pipeline ditch while utilizing a conventional dump truck for metering the padding material into the trough thereof. The padding machine of this invention also includes improvements in a conveyor system which delivers the padding material into the bottom of the ditch and atop the pipe in a new and improved manner. The padding machine of this invention achieves new and unexpected results not found in the above prior art.